In 2006, the National Center for Postsecondary Research, of which is MDRC is a partner, launched a demonstration of one-semester learning community programs at six colleges; five of these programs focused on developmental education. This is the final report from the project and includes findings from analyses that pool data across these five programs as well as the results for developmental education students at a sixth program at Kingsborough Community College, operated earlier under the Opening Doors demonstration. Across the six programs, almost 7,000 students were randomly assigned, about half into 174 learning communities, and tracked for three semesters. Key findings suggest that when compared with business as usual, one-semester learning communities in developmental education, on average, lead to: (1) A modest (half-credit) estimated impact on credits earned in the targeted subject (English or mathematics) but no impact on credits earned outside the targeted subject; (2) A modest (half-credit) estimated impact on total credits earned; and (3) No impact on persistence in college. The developmental education students in the Kingsborough program, which had some different features from the other five programs, including enhanced support services, showed somewhat larger results than the other sites in credits earned in the targeted subject. An MDRC report on the overall Kingsborough learning communities program, which served "both" developmental and college-ready students, shows a positive impact on degree attainment after six years. The graduation effect was driven primarily by students who had placed into college-level English, although there is also evidence that the program had a positive impact on long-term outcomes for students with the greatest developmental needs in English. Together, these evaluations suggest that, while most typical one-semester learning communities for developmental education students are not likely to lead to large effects on students' outcomes, a program with additional supports can have longer-term impacts for developmental students. Appended are: (1) Impact Analyses; (2) Supplementary Exhibits for Chapter 3; (3) Instructor Survey Details; (4) Cost Details; and (5) Supplementary Table for Chapter 5. Individual chapters contain footnotes. (Contains 25 tables, 10 figures and 2 boxes.) [This paper was written with Jedediah Teres and Kelley Fong. For "The Effects of Learning Communities for Students in Developmental Education: A Synthesis of Findings from Six Community Colleges. Executive Summary," see ED533826.]